This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Appreciation for theoretical approaches in biology has been increasing over the past decade as biologists have recognized that many problems in integrative biology require theory. At the same time, physicists have been caught up in the excitement generated by rapid advances in biological research. Signal transduction, in general, and protein kinases, in particular, provide an excellent and highly dynamic model system where these theoretical tools can be applied to individual proteins as well as to networks of interacting proteins that are mediated by protein phosphorylations. The pathways, the protein kinases themselves, and the protein:protein and protein:ligand interactions that dictate their function are all highly dynamic.